The deflection in a moving coil galvanometer is reduced to half when it is shunted with a $X \ \Omega$ coil. The relation between $X$ and the resistance of the galvanometer $G$ is:

The pole pieces of the magnet used in a pivoted coil galvanometer are

$A$ galvanometer having a coil resistance of $100 \ \Omega$ gives a full-scale deflection when a current of $1 \ mA$ is passed through it. The value of the shunt resistance,which can convert this galvanometer into an ammeter giving a full-scale deflection for a current of $10 \ A$,is: ...... $\Omega$

$A$ galvanometer of $100\,\Omega$ resistance gives full-scale deflection when $10\,mA$ of current is passed. To convert it into a $10\,A$ range ammeter,the resistance of the shunt required will be ............... $\Omega$.

The value of shunt resistance,that allows only $10 \%$ of the main current to pass through a galvanometer of resistance $99 \Omega$,is (in $Omega$)

$A$ student connects a voltmeter,an ammeter,and a resistor as shown in the circuit. If the voltmeter reading is $20 \ V$ and the ammeter reading is $4 \ A$,then the resistance $R$ will be: